Mopar Muscle Association UK

Welcome aboard Izzy!

That 383 spec is a little different...stand by for three thousand different suggestions...apart from the choice of performance pistons!

It does not need a lot to get 13-14s from a 383. Sub 13s is something else so make up your mind.

With a decent compression ratio, cam, mild head work and headers you can easily make it into the 13s.

But have a look at the 440 block my mate was selling (or selling- he can't make his mind up). http://www.moparuk.com/forums/viewtopic ... 616#129616

Idealy you need something like that. It comes at a price though.

Light H-beam rods and light pistons.

You want around 9.5 to 10:1 static compression if you use iron heads and around 10.5-11:1 ratio with ally heads.

The lower figure is for milder cams and the higher for hotter cams.

My mate was going to use Edelbrock heads so he was going for a zero deck height to get an 11:1 compression ratio combined with a hot solid tappet camshaft.

This 440 would probably get you in the 11s. But the same basic block in the 383 size with a milder cam would still get you into the 12s.

So have a think about it and decide either exactly how fast you want to go or exactly how much power you want to make with it.

If you intend to use a 2800 stall convertor then you can't go too wild on the cam anyway. You usually pick the converter to suit the cam - not the other way around.

My Challenger runs in the 11s and idles well (if a bit loud) in traffic. It revs to 6500 and has a 3000+ converter. But it drives really easily and sounds agressive. I used to use it to go to work every summer.

Tell me how fast you want and I can tell you what HP you need.

Hi Izzy


Dave,

I would like mid 13's every time. Any ideas on BHP?

I think you will struggle trying to find an off the shelf flat top piston that will give you around 10.1 at zero deck height which is what you should be aiming for with an iron head. Cheap aftermarket pistons for 383's usually come out at around 8.5.1 with the piston a fair way down the bore, no good for high performance. You want the piston at zero deck so that with a 40 thou gasket you get 40thou quench which is best to prevent detonation.

Idealy I would need to know the exact weight of the car Clivey but in general you want to aim for around 98-100mph at the end of the quarter to make mid 13s.
That works out at around 300HP at the rear wheels. So figure about 375hp at the crank.

And no. The "375hp" 4404bbl does NOT make anything like 375hp in real life and neither does the six pack.

A lot depends on the gearing as well. Gay gears will reduce the ET. But the milder the car and fatter/flatter the torque curve) the less important gearing is IMO.

Blue wrote:I think you will struggle trying to find an off the shelf flat top piston that will give you around 10.1 at zero deck height which is what you should be aiming for with an iron head.

Also it is probably cheaper to fit Edelbrock heads than fit big valves and do any porting on the iron heads if you intended doing anything like that. Plus the Edelbrocks have smaller chambers and increase the compression.

I agree, no point spending much money on iron heads these days.

Dave wrote:
And no. The "375hp" 4404bbl does NOT make anything like 375hp in real life and neither does the six pack.

.

....but.....but.... the books, they all say......

Advertised power outputs were notoriously misleading, it all depends who they were trying to fool at the time, 340's and Hemi's were deliberatly downrated to fit into certain classes for racing, I'm sure I read somewhere that the 425hp Hemi actually put out more than that...

Though many road tests put the six pack up there with the Hemi, so who do you believe?

Blue wrote: I'm sure I read somewhere that the 425hp Hemi actually put out more than that...

Well I have heard people say that but one of the guys that actually ran them on the dyno says that was a correct figure. But again this was on a dyno and not in a car....

Again. Who do you believe?

The hemi was rated 30hp more than the 440+6 but the Hemi made its power at higher rpms. This made the 440+6 about equal to it in the first part of a standing start race but once up on the powerband the Hemi would start to pick up more speed.

Not a huge difference when stock at all.

The main difference between these two RB engines is the potential for power.

Remember the 440 was tuned UP. The street hemi was tuned DOWN.

Don't forget all the lies for the insurance man Just who was tellling the truth?